WO2023042769A1 - 光ファイバ - Google Patents
光ファイバ Download PDFInfo
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- WO2023042769A1 WO2023042769A1 PCT/JP2022/033951 JP2022033951W WO2023042769A1 WO 2023042769 A1 WO2023042769 A1 WO 2023042769A1 JP 2022033951 W JP2022033951 W JP 2022033951W WO 2023042769 A1 WO2023042769 A1 WO 2023042769A1
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- refractive index
- optical fiber
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- core layer
- side core
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 75
- 239000012792 core layer Substances 0.000 claims abstract description 58
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 20
- 230000005540 biological transmission Effects 0.000 claims description 15
- 235000012239 silicon dioxide Nutrition 0.000 claims description 10
- 239000000460 chlorine Substances 0.000 claims description 6
- 229910052801 chlorine Inorganic materials 0.000 claims description 5
- 239000011734 sodium Substances 0.000 claims description 5
- 229910052700 potassium Inorganic materials 0.000 claims description 4
- 229910052708 sodium Inorganic materials 0.000 claims description 4
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 3
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 3
- 239000011591 potassium Substances 0.000 claims description 3
- 239000000835 fiber Substances 0.000 claims 1
- 238000005253 cladding Methods 0.000 abstract description 5
- 230000000052 comparative effect Effects 0.000 description 15
- 238000000034 method Methods 0.000 description 11
- 238000010586 diagram Methods 0.000 description 10
- 239000002019 doping agent Substances 0.000 description 10
- 239000000463 material Substances 0.000 description 10
- 238000004519 manufacturing process Methods 0.000 description 9
- 238000009826 distribution Methods 0.000 description 7
- 239000011521 glass Substances 0.000 description 7
- 229910052731 fluorine Inorganic materials 0.000 description 6
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 5
- 238000011156 evaluation Methods 0.000 description 5
- 239000011737 fluorine Substances 0.000 description 5
- 230000003287 optical effect Effects 0.000 description 5
- 239000000377 silicon dioxide Substances 0.000 description 3
- 239000000470 constituent Substances 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 240000007594 Oryza sativa Species 0.000 description 1
- 235000007164 Oryza sativa Nutrition 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000004071 soot Substances 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 238000004017 vitrification Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02004—Optical fibres with cladding with or without a coating characterised by the core effective area or mode field radius
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02004—Optical fibres with cladding with or without a coating characterised by the core effective area or mode field radius
- G02B6/02009—Large effective area or mode field radius, e.g. to reduce nonlinear effects in single mode fibres
- G02B6/02014—Effective area greater than 60 square microns in the C band, i.e. 1530-1565 nm
- G02B6/02019—Effective area greater than 90 square microns in the C band, i.e. 1530-1565 nm
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02042—Multicore optical fibres
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
- G02B6/0281—Graded index region forming part of the central core segment, e.g. alpha profile, triangular, trapezoidal core
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
- G02B6/0283—Graded index region external to the central core segment, e.g. sloping layer or triangular or trapezoidal layer
- G02B6/0285—Graded index layer adjacent to the central core segment and ending at the outer cladding index
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03605—Highest refractive index not on central axis
- G02B6/03611—Highest index adjacent to central axis region, e.g. annular core, coaxial ring, centreline depression affecting waveguiding
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
- G02B6/03622—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 2 layers only
- G02B6/03627—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 2 layers only arranged - +
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
- G02B6/03638—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only
- G02B6/0365—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only arranged - - +
Definitions
- the present invention relates to optical fibers.
- Patent Document 1 A technique for doping a clad portion with a dopant such as fluorine in order to lower the refractive index of glass in a single-mode optical fiber has been disclosed (Patent Document 1).
- a dopant such as fluorine
- Patent Document 2 A technique for doping a clad portion with a dopant such as fluorine in order to lower the refractive index of glass in a single-mode optical fiber has been disclosed (Patent Document 1).
- a dopant such as fluorine
- an optical fiber that employs a W-shaped refractive index profile is being actively studied (Patent Document 2).
- W-shaped refractive index profiles have been employed, for example, to increase the effective core area of optical fibers.
- An optical fiber having a large effective core area suppresses the occurrence of nonlinear optical effects in the optical fiber, and thus can be suitably used as, for example, a long-distance optical transmission line.
- a dopant such as fluorine that lowers the refractive index of the glass.
- the transmission loss and the macrobend loss are reduced.
- the present invention has been made in view of the above, and its object is to provide an optical fiber with reduced transmission loss and macrobend loss.
- one aspect of the present invention includes a core portion, a side core layer surrounding the outer periphery of the core portion, and a clad portion surrounding the outer periphery of the side core layer,
- the average maximum relative refractive index difference of the core portion with respect to the average refractive index of the clad portion is ⁇ 1
- the relative refractive index difference of the average refractive index of the side core layer is ⁇ 2
- the average refractive index of the clad portion with respect to pure silica glass is
- 2a is the core diameter of the core portion and 2b is the outer diameter of the side core layer
- 2a is 8 ⁇ m or more and 10 ⁇ m or less
- 2b is 35 ⁇ m or more and 45 ⁇ m or less
- the side core There is a bottom portion with a lower refractive index than other regions of the layer, and the distance from the center of the core portion to the position of the lowest refractive index in the bottom portion is a + (ba) / 1.55 [ ⁇ m] or less.
- the bottom portion may be a portion where the refractive index changes abruptly in the refractive index profile of the side core layer and a portion where the refractive index profile has an inflection point.
- the absolute value of ⁇ B may be 0.03% or more and 0.07% or less.
- the distance from the center of the core portion to the position of the lowest refractive index in the bottom portion may be a+(ba)/1.8 [ ⁇ m] or more.
- a mode field diameter of 8.6 ⁇ m or more and 9.5 ⁇ m or less at a wavelength of 1310 nm may be used.
- the MAC value which is the value obtained by dividing the mode field diameter at a wavelength of 1310 nm by the cable cutoff wavelength, may be 7.0 or more and 7.2 or less.
- the core portion may contain at least one of chlorine, potassium, and sodium.
- the transmission loss at a wavelength of 1550 nm may be 0.35 dB/km or less.
- the macrobend loss at a wavelength of 1550 nm when wound for 10 turns with a diameter of 30 mm may be 0.03 dB or less.
- FIG. 1 is a schematic cross-sectional view of an optical fiber according to an embodiment.
- FIG. 2 is a schematic diagram of the refractive index profile of the optical fiber according to the embodiment.
- FIG. 3 is a schematic diagram of a main part of a refractive index profile of an optical fiber according to a comparative example.
- FIG. 4 is a schematic diagram of the main part of the refractive index profile of the optical fiber according to the embodiment.
- FIG. 5 is a diagram showing an example of a bulk density distribution profile of a porous preform used for manufacturing an optical fiber according to a comparative embodiment.
- FIG. 6 is a diagram showing an example of a bulk density distribution profile of a preform used for manufacturing the optical fiber according to the embodiment.
- the cutoff wavelength or the effective cutoff wavelength refers to the ITU-T G.I. 650.1, the cable cutoff wavelength.
- G.I. 650.1 and G.I. 650.2 shall comply with the definition and measurement method.
- FIG. 1 is a schematic cross-sectional view of an optical fiber according to an embodiment.
- the optical fiber 10 is made of silica-based glass, and includes a core portion 11 , a side core layer 12 surrounding the outer periphery of the core portion 11 , and a clad portion 13 surrounding the outer periphery of the side core layer 12 .
- the optical fiber 10 may include a coating layer surrounding the outer circumference of the clad portion 13 .
- FIG. 2 is a diagram showing the refractive index profile of the optical fiber 10.
- FIG. A profile P1 is a refractive index profile of the core portion 11 and has a so-called step shape.
- Profile P2 is the refractive index profile of the side core layer 12 .
- a profile P3 is a refractive index profile of the cladding portion 13 .
- the refractive index profile of the core portion 11 is not limited to a geometrically ideal step shape, but the shape of the top portion is not flat and unevenness is formed due to manufacturing characteristics. It may have a shape that pulls.
- the refractive index of the substantially flat region at the top of the refractive index profile within the range of the core diameter 2a of the core portion 11 in manufacturing design serves as an index for determining ⁇ 1.
- the core diameter of the core portion 11 is 2a.
- the outer diameter of the side core layer 12 is 2b.
- the relative refractive index difference (maximum relative refractive index difference) of the average maximum refractive index of the core portion 11 with respect to the average refractive index of the clad portion 13 is ⁇ 1.
- the relative refractive index difference of the average refractive index of the side core layer 12 with respect to the average refractive index of the cladding portion 13 is ⁇ 2.
- the average maximum refractive index of the core portion 11 is the average value in the radial direction of the refractive index of the substantially flat region at the top of the refractive index profile.
- the average refractive index of the side core layer 12 and the clad portion 13 is the average value of the refractive indices in the radial direction of the refractive index profile.
- the relative refractive index difference of the average refractive index of the clad portion 13 with respect to the refractive index of pure silica glass is ⁇ Clad.
- pure silica glass is very high-purity silica glass that does not substantially contain dopants that change the refractive index and has a refractive index of about 1.444 at a wavelength of 1550 nm.
- the dashed-dotted line indicates the relative refractive index difference of the pure silica glass with respect to the average refractive index of the cladding portion 13 .
- the zero line indicating the relative refractive index difference of pure silica glass is indicated by a dashed line.
- the optical fiber 10 has a W-shaped refractive index profile.
- FIG. 2 shows a case where ⁇ Clad is less than 0%, ⁇ Clad may be 0% or more.
- the core portion 11 is made of silica-based glass containing a dopant for adjusting the refractive index.
- the core portion 11 contains at least one of chlorine (Cl) potassium (K) and sodium (Na) as a dopant.
- the core portion 11 may further contain fluorine (F) for refractive index adjustment and glass viscosity adjustment. F lowers the refractive index of quartz glass, and Cl, K and Na are dopants that raise the refractive index of quartz glass.
- the core portion 11 may contain germanium (Ge), which is a dopant that increases the refractive index of quartz glass.
- the side core layer 12 and the clad portion 13 are made of silica-based glass to which only F and Cl are added.
- ⁇ 1> ⁇ Clad> ⁇ 2 and 0> ⁇ 2 are established, and preferable exemplary ranges of ⁇ 1, ⁇ 2, and ⁇ Clad described later are realized.
- ⁇ 1 is 0.35% or more and 0.45% or less
- ⁇ 2 is ⁇ 0.2% or more and less than 0%
- 2a is 8 ⁇ m or more and 10 ⁇ m
- 2b is 35 ⁇ m or more and 45 ⁇ m or less.
- ⁇ Clad is, for example, ⁇ 0.01%.
- the optical fiber 10 has a mode field diameter (MFD) of 8.6 ⁇ m or more and 9.5 ⁇ m or less at a wavelength of 1310 nm. Further, for example, the optical fiber 10 has a macrobend loss of 0.03 dB or less at a wavelength of 1550 nm when wound for 10 turns with a diameter of 30 mm. Also, for example, the optical fiber 10 is G.I. 652, the transmission loss at a wavelength of 1550 nm is 0.35 dB/km or less. Further, the transmission loss of the optical fiber 10 at a wavelength of 1550 nm is more preferably 0.2 dB/km or less.
- MFD mode field diameter
- the optical fiber 10 has a macrobend loss of 0.03 dB or less at a wavelength of 1550 nm when wound for 10 turns with a diameter of 30 mm.
- the optical fiber 10 is G.I. 652, the transmission loss at a wavelength of 1550 nm is 0.35 dB/km or less. Further,
- the MAC value which is the value obtained by dividing the mode field diameter (MFD) at a wavelength of 1310 nm by the cable cutoff wavelength ( ⁇ cc), is, for example, 7.0 or more and 7.2 or less.
- the MAC value is one index for evaluating macrobend loss characteristics, and optical fibers with similar MAC values have similar macrobend loss characteristics.
- the refractive index profile of the side core layer 12 has a bottom portion having a lower refractive index than other regions of the side core layer 12. Further, the distance from the center of the core portion 11 to the position of the lowest refractive index in the bottom portion is a+(ba)/1.55 [ ⁇ m] or less.
- FIG. 4 is a schematic diagram of the main part of the refractive index profile of the optical fiber according to the embodiment.
- the refractive index profiles of the core portion 11 and the side core layer 12 of the optical fiber 10 are indicated by solid lines.
- the refractive index profile of the side core layer 12 of the optical fiber 10 has a bottom portion 14 having a lower refractive index than other regions of the side core layer 12 .
- the bottom portion 14 is, for example, a portion where the refractive index changes abruptly in the refractive index profile of the side core layer 12 and has an inflection point in the refractive index profile.
- an optical fiber that employs a W-shaped refractive index profile when manufacturing an optical fiber that employs a W-shaped refractive index profile, a known method such as the VAD (Vapor Axial Deposition) method or the OVD (Outside Vapor Deposition) method is used.
- VAD Vehicle Axial Deposition
- OVD Outside Vapor Deposition
- An optical fiber preform was produced by using the above method, and an optical fiber was drawn from this optical fiber preform. It was confirmed. Assuming that the relative refractive index difference of the lowest refractive index of the bottom portion 14 with respect to the average refractive index of the side core layer 12 is ⁇ B, the absolute value of ⁇ B is, for example, 0.03% or more and 0.07% or less.
- the distance (r in FIG. 4) from the center of the core portion 11 to the position where the refractive index in the bottom portion 14 is lowest is a+(b ⁇ a)/1 It was found that transmission loss and macrobend loss are reduced when the thickness is 0.55 [ ⁇ m] or less.
- the distance r is a+(b ⁇ a)/1.8 [ ⁇ m] or more.
- FIG. 3 is a schematic diagram of the main part of the refractive index profile of the optical fiber according to the comparative embodiment.
- the optical fiber according to the comparative embodiment is an optical fiber that differs from the optical fiber 10 according to the embodiment only in the refractive index profile of the side core layer.
- FIG. 3 broken lines indicate refractive index profiles of the core portion 11A and the side core layer 12A of the optical fiber 10A according to the comparative embodiment.
- a relative refractive index difference of the average refractive index of the side core layer 12A with respect to the average refractive index of the clad portion is defined as ⁇ 2′.
- a bottom portion 14A also exists in the refractive index profile of the side core layer 12A of the optical fiber 10A.
- the absolute value of the relative refractive index difference ⁇ B' of the lowest refractive index of the bottom portion 14A with respect to the average refractive index of the side core layer 12A is, for example, 0.03% or more and 0.07% or less.
- the distance (r' in FIG. 4) from the center of the core portion 11A to the position of the lowest refractive index in the bottom portion 14A is larger than a+(b ⁇ a)/1.55 [ ⁇ m]. That is, the bottom portion 14A is located relatively close to the clad portion with respect to the core portion 11A. As a result, the optical fiber 10A becomes an optical fiber whose transmission loss and macrobend loss are not reduced compared to the optical fiber 10.
- the present inventors simultaneously formed the core portion of the optical fiber and the portion to be the side core layer by the VAD method, and added fluorine to the side core layer to make it porous.
- a base material was prepared and vitrified and sintered to prepare a core base material.
- the core base material may also be produced by the following method. That is, the VAD method is used to fabricate a porous preform having a core portion of an optical fiber and a portion to be a side core layer. Then, in order to dope F into the part of the soot that will become the side core layer, fluorine gas is flowed in the vitrification sintering process to prepare a core base material. Further, the OVD method is used to form a porous layer that will become the clad portion on the core preform thus produced, and this is vitrified and sintered to produce an optical fiber preform. Then, an optical fiber is drawn from this optical fiber preform.
- FIG. 5 is a diagram showing an example of a bulk density distribution profile of a porous base material used for manufacturing an optical fiber according to a comparative embodiment.
- Reference numeral 110A denotes a portion that becomes the core portion 11A
- reference numeral 120A denotes a portion that becomes the side core layer 12A.
- FIG. 5 shows the distribution profile of the bulk density at three locations in the longitudinal direction of the porous base material, ie, the upper, middle and lower portions.
- the porous base material shown in FIG. 5 there is a part where the bulk density is locally increased in the part 120A as circled, and the variation in the bulk density between the upper part, the middle part and the lower part is large. Such variations and local variations in bulk density are considered to cause variations in doping amount when F is doped. Further, when such variations in bulk density and local fluctuations are large, the bottom portion 14A in the side core layer 12A is positioned relatively close to the clad portion.
- the inventors improved the directivity of the flame in the burner used for depositing the glass particles in the VAD method in order to suppress variations in bulk density and the amount of local increase.
- a straightening plate is installed in the furnace of the VAD device to suppress the flow of air currents that disturb the directivity of the flame, and to increase the flow rate of the combustion-supporting gas (for example, oxygen) supplied to the burner to strengthen the directivity of the flame. rice field.
- FIG. 6 is a diagram showing an example of the bulk density distribution profile of the preform used for manufacturing the optical fiber according to the embodiment.
- Reference numeral 110 denotes a portion that becomes the core portion 11
- reference numeral 120 denotes a portion that becomes the side core layer 12 .
- FIG. 6 shows the distribution profile of the bulk density at three locations in the longitudinal direction of the porous base material, ie, the upper, middle and lower portions.
- the variation in bulk density and the amount of local increase in the portion 120 were suppressed.
- the bottom portion 14 of the optical fiber 10 is positioned closer to the core portion 11 than the bottom portion 14A of the optical fiber 10A, and r becomes a+(ba)/1.55 [ ⁇ m] or less.
- Example, Comparative Example Optical fibers of Examples 1 and 2 and optical fibers of Comparative Examples 1 and 2 corresponding to the above-described embodiment and comparative form were manufactured, and their characteristics were measured and evaluated. Table 1 shows structural parameters and measurement results or evaluation results of the manufactured optical fiber.
- the optical fibers of Examples 1 and 2 and Comparative Examples 1 and 2 had the same Q value (MAC value), which was 7.0 to 7.2.
- MAC value Q value
- the macrobend loss was measured at a wavelength of 1550 nm when the wire was wound for 10 turns with a diameter of 30 mm.
- the bottom position means the distance from the center of the core portion (the distance from the center of the core to the position of the bottom) at the position where the refractive index in the bottom portion is lowest.
- Evaluation 1 is an evaluation of the transmission loss at a wavelength of 1550 nm, and the case of 0.2 dB/km or less was evaluated as “O”, and the case of more than 0.2 dB/km was evaluated as “X”.
- evaluation 2 is an evaluation of macrobend loss, and for Example 1 and Comparative Example 1, “O” when it is 0.03 dB/km or less, and when it exceeds 0.03 dB/km.
- Example 2 and Comparative Example 2 the case of 0.5 dB/km or less was indicated by "O”, and the case of exceeding 0.5 dB/km was indicated by "X”.
- Table 1 transmission loss and macrobend loss were reduced, and good results were obtained.
- Example 1 the core diameter 2a was 8 ⁇ m.
- the outer diameter 2b of the side core layer was 38 ⁇ m.
- the average maximum relative refractive index difference ⁇ 1 of the core portion with respect to the average refractive index of the clad portion was 0.4%.
- the relative refractive index difference ⁇ 2 of the average refractive index of the side core layer with respect to the average refractive index of the clad portion was ⁇ 0.15%.
- the relative refractive index difference ⁇ Clad of the average refractive index of the clad portion with respect to the refractive index of pure silica glass was ⁇ 0.01%.
- the distance from the core center to the bottom position was 12.3 ⁇ m (a+(ba)/1.55 [ ⁇ m] or less).
- the relative refractive index difference ⁇ B of the lowest refractive index of the bottom portion with respect to the average refractive index of the side core layer was ⁇ 0.07%.
- the mode field diameter at a wavelength of 1310 nm was 8.64 ⁇ m, and the Q value was 7.0.
- the core diameter 2a was 8 ⁇ m.
- the outer diameter 2b of the side core layer was 38 ⁇ m.
- the average maximum relative refractive index difference ⁇ 1 of the core portion with respect to the average refractive index of the clad portion was 0.4%.
- the relative refractive index difference ⁇ 2 of the average refractive index of the side core layer with respect to the average refractive index of the clad portion was ⁇ 0.15%.
- the relative refractive index difference ⁇ Clad of the average refractive index of the clad portion with respect to the refractive index of pure silica glass was ⁇ 0.01%.
- the distance from the core center to the bottom position was 14.0 ⁇ m (larger than a+(ba)/1.55 [ ⁇ m]).
- the relative refractive index difference ⁇ B ( ⁇ B') of the lowest refractive index of the bottom portion with respect to the average refractive index of the side core layer was ⁇ 0.07%.
- the mode field diameter at a wavelength of 1310 nm was 8.58 ⁇ m, and the Q value was 7.0.
- the core diameter 2a was 8.5 ⁇ m.
- the outer diameter 2b of the side core layer was 40 ⁇ m.
- the average maximum relative refractive index difference ⁇ 1 of the core portion with respect to the average refractive index of the clad portion was 0.37%.
- the relative refractive index difference ⁇ 2 of the average refractive index of the side core layer with respect to the average refractive index of the clad portion was ⁇ 0.19%.
- the relative refractive index difference ⁇ Clad of the average refractive index of the clad portion with respect to the refractive index of pure silica glass was ⁇ 0.01%.
- the distance from the core center to the bottom position was 14.4 ⁇ m (a+(ba)/1.55 [ ⁇ m] or less).
- the relative refractive index difference ⁇ B of the lowest refractive index of the bottom portion with respect to the average refractive index of the side core layer was ⁇ 0.03%.
- the mode field diameter at a wavelength of 1310 nm was 8.97 ⁇ m, and the Q value was 7.1.
- the core diameter 2a was 8.5 ⁇ m.
- the outer diameter 2b of the side core layer was 40 ⁇ m.
- the average maximum relative refractive index difference ⁇ 1 of the core portion with respect to the average refractive index of the clad portion was 0.37%.
- the relative refractive index difference ⁇ 2 of the average refractive index of the side core layer with respect to the average refractive index of the clad portion was ⁇ 0.19%.
- the relative refractive index difference ⁇ Clad of the average refractive index of the clad portion with respect to the refractive index of pure silica glass was ⁇ 0.01%.
- the distance from the core center to the bottom position was 18.4 ⁇ m (larger than a+(b ⁇ a)/1.55 [ ⁇ m]).
- the relative refractive index difference ⁇ B ( ⁇ B′) of the lowest refractive index of the bottom portion with respect to the average refractive index of the side core layer was ⁇ 0.03%.
- the mode field diameter at a wavelength of 1310 nm was 9.22 ⁇ m and the Q value was 7.2.
- the present invention is not limited by the above embodiments.
- the present invention also includes those configured by appropriately combining the respective constituent elements described above. Further effects and modifications can be easily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the above-described embodiments, and various modifications are possible.
- the present invention is suitable for application to optical fibers as optical transmission lines.
- optical fiber 11 core portion 12: side core layer 13: clad portion 14: bottom portion 120: portions P1, P2, P3: profile
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Abstract
Description
図1は、実施形態に係る光ファイバの模式的な断面図である。光ファイバ10は、石英系ガラスからなり、コア部11と、コア部11の外周を取り囲むサイドコア層12と、サイドコア層12の外周を取り囲むクラッド部13と、を備える。なお、光ファイバ10は、クラッド部13の外周を取り囲む被覆層を備えていてもよい。
上記実施形態および比較形態にそれぞれ対応する実施例1、2の光ファイバおよび比較例1、2の光ファイバを製造し、その特性を測定し、評価した。製造した光ファイバの構造パラメータと測定結果または評価結果を表1に示す。なお、実施例1、2、比較例1、2の光ファイバでは、Q値(MAC値)はいずれも等しく、7.0~7.2の値とした。またマクロベンド損失として、直径30mmで10turn巻いた際の波長1550nmにおけるマクロベンド損失を測定した。なお、ボトム位置とは、ボトム部における屈折率が最低の位置の、コア部の中心からの距離(コア中心からボトムの位置までの距離)を意味する。また、「評価1」とは、波長1550nmにおける伝送損失の評価であって、0.2dB/km以下の場合を「〇」とし、0.2dB/kmを超える場合を「×」とした。また、「評価2」とは、マクロベンド損失の評価であって、実施例1、比較例1については、0.03dB/km以下の場合を「〇」、0.03dB/kmを超える場合を「×」とし、実施例2、比較例2については、0.5dB/km以下の場合を「〇」、0.5dB/kmを超える場合を「×」とした。表1から解るように、実施例1、2では、伝送損失およびマクロベンド損失が低減され、良好な結果が得られた。
11 :コア部
12 :サイドコア層
13 :クラッド部
14 :ボトム部
120 :部分
P1、P2、P3 :プロファイル
Claims (9)
- コア部と、
前記コア部の外周を取り囲むサイドコア層と、
前記サイドコア層の外周を取り囲むクラッド部と、
を備え、
前記クラッド部の平均屈折率に対する、前記コア部の平均の最大比屈折率差をΔ1、前記サイドコア層の平均屈折率の比屈折率差をΔ2とし、純石英ガラスに対する前記クラッド部の平均屈折率の比屈折率差をΔCladとすると、Δ1>ΔClad>Δ2かつ0>Δ2が成り立ち、
Δ1が0.35%以上0.45%以下であり、
Δ2が-0.2%以上0%未満であり、
前記コア部のコア径を2a、前記サイドコア層の外径を2bとしたときに、2aが8μm以上10μm以下、2bが35μm以上45μm以下であり、
前記サイドコア層の屈折率プロファイルにおいて、当該サイドコア層の他の領域よりも屈折率が低いボトム部が存在し、
前記ボトム部における屈折率が最低の位置の、前記コア部の中心からの距離が、a+(b-a)/1.55[μm]以下である
光ファイバ。 - 前記ボトム部は、前記サイドコア層の屈折率プロファイルにおいて、屈折率が急激に変化する部分であって、屈折率プロファイルが変曲点を有する部分である
請求項1に記載の光ファイバ。 - 前記サイドコア層の平均屈折率に対する、前記ボトム部の最低屈折率の比屈折率差をΔBとすると、ΔBの絶対値が0.03%以上0.07%以下である
請求項1に記載の光ファイバ。 - 前記ボトム部における屈折率が最低の位置の、前記コア部の中心からの距離が、a+(b-a)/1.8[μm]以上である
請求項1に記載の光ファイバ。 - 波長1310nmにおけるモードフィールド径が8.6μm以上9.5μm以下である
請求項1に記載の光ファイバ。 - 波長1310nmにおけるモードフィールド径をケーブルカットオフ波長で除算した値であるMAC値が7.0以上7.2以下である
請求項1に記載の光ファイバ。 - 前記コア部は、塩素、カリウム、ナトリウムのうち少なくとも一つを含む
請求項1に記載の光ファイバ。 - 波長1550nmにおける伝送損失が0.35dB/km以下である
請求項1に記載の光ファイバ。 - 直径30mmで10turn巻いた際の波長1550nmにおけるマクロベンド損失が0.03dB以下である
請求項1に記載の光ファイバ。
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JP2009122277A (ja) | 2007-11-13 | 2009-06-04 | Furukawa Electric Co Ltd:The | 光ファイバおよび光伝送システム |
WO2019142878A1 (ja) * | 2018-01-19 | 2019-07-25 | 古河電気工業株式会社 | 光ファイバ母材の製造方法及び光ファイバ母材並びに光ファイバの製造方法及び光ファイバ |
JP6690296B2 (ja) | 2016-02-26 | 2020-04-28 | 住友電気工業株式会社 | 光ファイバ |
US20210032153A1 (en) * | 2019-07-30 | 2021-02-04 | Corning Incorporated | Tension-based methods for forming bandwidth tuned optical fibers for bi-modal optical data transmission |
WO2021187475A1 (ja) * | 2020-03-17 | 2021-09-23 | 住友電気工業株式会社 | 光ファイバ |
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JP2009122277A (ja) | 2007-11-13 | 2009-06-04 | Furukawa Electric Co Ltd:The | 光ファイバおよび光伝送システム |
JP6690296B2 (ja) | 2016-02-26 | 2020-04-28 | 住友電気工業株式会社 | 光ファイバ |
WO2019142878A1 (ja) * | 2018-01-19 | 2019-07-25 | 古河電気工業株式会社 | 光ファイバ母材の製造方法及び光ファイバ母材並びに光ファイバの製造方法及び光ファイバ |
US20210032153A1 (en) * | 2019-07-30 | 2021-02-04 | Corning Incorporated | Tension-based methods for forming bandwidth tuned optical fibers for bi-modal optical data transmission |
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